Cross blast circuit breaker with arcing contacts controlling orifice of arcing chamber



y 14, 1953 c. D. AINSWORTH 2,645,694

CROSS BLAST CIRCUIT BREAKER WITH ARCING CONTACTS CONTROLLING ORIFICE OFARCING CHAMBER Filed Feb. 15, 1949 Patented July 14, 1953' CROSS BLASTCIRCUIT BREAKER ITH ARCING CONTACTS CONTROLLING ORIFICEV or ARCINGCHAMBER Chester D. Ainsworth, Wollaston, Mass, assignor toAllis-Chalmers Manufacturing Company,

Milwaukee, Wis., a corporation .of Delaware Application February 15,1949, Serial No. 76,468

1 This invention relates to switching devices such as electric circuitbreakers of the fluid blast type and more particularly to means forimproving the interrupting capacity thereof. I V

In the operation of circuit breakers of the fluid blast type, thecurrent interruption takes place under the most advantageous conditionswhen thearcing contacts are rapidly separated to permit theflow'therebetween of a blast of fluid of maximum velocity obtainablefrom the available source. In orderto be sure that restriking of the arcdoes not occur, isolating or disconnect contacts are frequently providedin addition to the arcing contacts and are opened after the arc has beenextinguished butwhile the fluid blast is still being maintained. I

Heretofore, axialt'ype air blast circuit breaks ers employing a nozzletype fixed contact having an annular or circular contact surface and acooperating movable plug contact have been used. At the time ofseparationof this type of contact, a small annular or circular gap isformed therebetween and the are formed upon separation thereof, duringits state of inception,

extends transversely across the gap. Theblast this is conducive to lowinterrupting efficiency of the axial air blast circuit breaker using 00-operating nozzle and plug type arcing contacts. The above describedlimitations of the axial type circuit breaker employing cooperatingnozzle and plug'type arcing contacts led to the development of axialtype circuit breakers having diflierent types of arcing contactarrangements. One of the contact arrangements developed for interruptionof high currents comprised an insulating gas blast nozzle and a pair ofbutt contacts arranged therein and separable in a directionlongitudinally thereof. This type of arrangement proved to be capable ofinterrupting currents of higher magnitude than was possible witharrangements having nozzle and plug contacts, yet it had a definitedrawback consisting in the fact that the upstream contact was animpediment limiting the effectiveness of'the air blast along the zone ofthe common geometrical axis of both contacts.

'5 Claims. (Cl. 200-448) 2 It is'therefore" one object of the presentinvention to provide a new and improved circuit breaker of the fluidblast type in which substantially all of the fluid passing through thecircuit breaker over the engageable surfaces of its contacts flows insubstantially a single direction transversely of the direction ofseparation of the arcing contacts.

A further object of the present invention is to provide a new andimproved circuit breaker of the fluid blast type in which substantiallyall of the fluid blast is utilized in extinguishing the are formed uponseparation'of arcing contacts embodied therein.

A still further object of the present invention is to provide a'new andimproved circuit breaker of the fluid blast type in which the fluidblast is controlled and directed by the arcing contact structure. 7

Objects and advantages other than those set forth will be apparent fromthe following description when read in connection with the accompanyingdrawings in which:

Fig. l is a diagrammatic view. partly in elevation of a circuit breakerembodying the present invention;

Fig. 2 is an enlarged view of an axial cross section through theinterrupting head of the circuit breaker illustrated in Fig. 1; and

ment thereof a reservoir 2 constituting a source of supply fluid underpressure, which will be assumed herein to be compressed air, suppliedfrom a suitable compressor (not shown). Al-

though in gener'al, circuit breakers of the type herein considered areprovided with a plurality of similar switch elements or pole units to beinserted in the several conductors of a polyphase electric circuit, onlyone such pole unit is shown in Fig. 1 and the circuit breaker will bedescribed in detail as if it were of the single pole typ The circuitbreaker, for example, may comprise a fixed arcing contact 3 and acooperating movable arcing contact 4 having mutually engageable surfacesconnected in series with a I disconnecting switch comprising a fixeddisconnect contact 5 and a cooperating movable disconnect contact 6 inan electric circuit through stud terminals 1 and 8. The arcing contacts3 and 4 are housed in a tubular arcing chamber 9 having a metallicsleeve shaped wall axially aligned with and supporting an insulatingsleeve II and an insulating sleeve 12. The metallic sleeve IU of chamber9 constitutes a conductive connection between the fixed arcing contact 3and an extension of terminal 8. Sleeve H constitutes a discharge passagewherein the are drawn between contacts 3 and 4 is forced by a gas blast.

Sleeve l 0, as more clearly illustrated in Fig. 2, is provided with aninwardly extendin bracket [3 upon which is arranged a contactconstituting the fixed arcing contact 3 of the circuit breaker. Contact3 forms an arc runner for directing the arc or are terminal downstreamof the zone of arc initiation and into the discharge passage H. Thecooperating movable arcing contact 4 is actuated by a piston 16 arrangedfor reciprocatory movement within a cylinder [4 which is axially alignedwithin insulating sleeve portion l2 and forms the cylinder for a fluidmotor [1. Insulating sleeve I2 is partially closed at the upper endthereof by a diaphragm or perforated transversal partition I8 providedwith apertures l9 and 20 for regulating the admission of air frommetallic sleeve I0. Piston I6 is thus rendered operable by means offluid under pressure introduced within sleeve H] for separating arcingcontacts 3 and 4.

The movable arcing contact 4 is urged into engagement with the fixedarcing contact 3 by resilient means such as a spring 2| acting between ashoulder 22 mounted on a piston rod 23 and partition I 8.

The movable disconnect contact 6 may be pivotally mounted on a bracket24 which is secured to an extension of terminal '1. One end of aninsulating connecting rod 25 may be connected to movable disconnectcontact 6 at a point 26 intermediate the ends thereof, and the other endA of rod 25 may be connected to an arm 21 of a bell crank 28. A secondarm 3| of bell crank 28 may be connected to a piston rod 32 of a fluidmotor 33. The rod 32 protrudes through and beyond the end of a cylinder34 of motor 33.

Motor 33 actuates the bell crank 28 which, in turn, actuates theconnecting rod 25. A predetermined movement of connecting rod 25actuates the movable disconnect contact and moves it to its open andclosed positions. A pair of regulating valves or needle valves 35 and 36may be utilized for regulating the supply of fluid from reservoir 2 tomotor 33.

A mechanical interlocking device for precluding improper sequence ofoperation of the disconnect corrtacts 5 and 6 with reference to thearcing contacts 3 and 4 is provided for proper circuit breakeroperation. The mechanical interlocking device comprises a bent lever 31which is pivotally mounted on a bracket 38 and arranged to lie withinthe path of relative movement of the arcing contacts, which, in theembodiment shown, is the path of movement of contact 4 or of the piston[6 which is actuated with contact 4. Lever 31 also lies in the path ofrelative movement of the disconnect contacts which, in the embodimentshown, is the path of movement of contact 6, for preventing separationof the disconnect contacts 5 and 6 prior to the opening of arcingcontacts 3 and 4. A biasing means, such as a spring 39, pivots the lever31 into the path of movement of the movable disconnect contact 6 andprevents separation thereof from the stationary or fixed disconnectcontact 5 in case of maladjustment 0f the means which control thesequence of the fluid motor for operating arcing contact 3.

The compressed air for operating the circuit breaker control system andthe arcing contacts is derived from the reservoir 2. The air underpressure in reservoir 2 also produces the are extinguishing blast acrossthe gap formed between the pair of cooperating arcing contacts 3 and 4upon separation thereof. The arc extinguishing blast from reservoir 2 tothe arcing contacts 3 and 4 is controlled by a blast valve 40 whichprovides a connection between the reservoir 2 and a conduit 4| which isconnected to the metallic sleeve portion In of chamber 9.

In accordance with the present invention arcing contacts 3 and 4 may bearranged to engage within a nozzle 42 which is preferably made ofrefractory insulating material and is arranged at the entrance of thepassage formed by chamber 9. Nozzle 42 establishes a zone of highvelocity for the blast of fluid under pressure supplied to chamber 9from reservoir 2 through conduit 41. In order to utilize substantiallyall of the arc extinguishing blast of fluid under pressure a means, suchas guiding surface 43 of nozzle 42 is provided for biasing the areformed upon initial separation of the arcing contacts 3 and 4 in adirection transverse to the direction of separation of the arcingcontacts. Guiding means 43 provide a substantially rectilinear paththrough a gap formed upon separation of the arcing contacts 3 and 4 forthe blast of gas under pressure.

The guiding means 43 which is arranged to provide a sinuous, tortuous orzigzag path comprises a first concave portion 44 extending from theupstream end of nozzle 42 to the area where the gap is formed uponseparation of the arcing contacts 3 and 4, a portion 45 extendingsubstantially parallel to the gap, a second concave portion 44aextending from the gap to the downstream end of nozzle 42. The portion45 extending generally parallel to the gap i substantially perpendicularto a longitudinal axis 60 of the gap and arcing contacts 3 and 4. Thus,the guiding means are so arranged that the blast of gas sweeps in asingle direction substantially the total contact engaging surface areas.

Arcing chamber 9 and particularly guiding means 43 incorporates thefeatures of a cross blast circuit breaker into a conventional axialblast circuit breaker structure, thereby combining desirable features ofboth types of breakers into a single breaker structure. By axiallyaligning sleeve I2, which contains the actuating means for arcingcontacts 3 and 4 and sleeve l0 and H a reduction of the overalldimension of the cross blast circuit breaker is obtained.

Fig. 3 illustrates more clearly the positioning of the portions 44, 45,and 44a which combine to form the guiding means 43 of nozzle 42.

The movable arcing contact 4 is so arranged as to control the amount ofgas under pressure passing through nozzle 42 prior to as Well as duringthe time of contact separation. Movable contact 4, when in the closedposition thereof, completely obstructs the orifice formed by the guidingmeans 43 of nozzle 42. In the open position thereof, movable contact 4directs substantially all of the fluid passing through the orifice overthe engageable surfaces of the arcing contacts 3 and 4. Sleeve ll maycontain an auxiliary arcing or probe electrode 41 which is usuallyaffixed thereto. The auxiliary arcing electrode 41 may be connected withthe stationary arcing con- .tact' through a current limiting resistor 48by 'means of a conductor 49.

tively, control the actuating means for the circuit breaker. Bothcontrol valves 55 and 56 are connected to reservoir 2 by a commonconduit 5?.

A slide or piston type interlocking valve 58 is provided and arranged ina conduit 59, 39 for connecting the closing valve 56 and the fluidoperated motor 33. This type of valve is more fully described andclaimed in a copending application Serial No. 71,506 of John F. Chipman,filed January 18, 1949, now Patent No. 2,533,559 issued December 12,1950.

The circuit breaker illustrated in Fig. 1 of the drawings is shown withthe disconnect contacts in the open position and the pneumatic controlsystem in the corresponding position. A closing operation is initiatedby energization of the closing solenoid valve 56, thereby causing airunder pressure from reservoir 2 to pass through conduit 51, valve 56,conduit 59, valve 58, conduit 59 to fluid motor 33., Operation ofsolenoid valve 56 results in a piston (not shown) of motor 33 movingfrom right to left to actuate rod 32, bell crank 28, and connecting rod25, thus closing the disconnect contacts 5 and 6. The movement of thepiston of fluid motor 33 from right to left rotates link 53 clockwise,and this results in an upward movement of connecting rod 52, which inturn rotates link 54 in a clockwise direction. The clockwise rotation oflink 55 actuates slide valve 53 in an upward direction, thus opening aport from trip valve 55 to blast valve 40.

When the solenoid trip valve 35 is energized, compressed air flows fromreservoir 2, through conduit 51, trip valve 55, and a conduit 68,through slide valve 50 and into blast valve 40. This initiates theoperation of blast valve 40. Upon being opened, blast valve it permits ablast of air under pressure to flow through conduit il, an inlet port 69of sleeve Hi, and into chamber 9. Air under pressure in chamber 9actuates piston I6 and piston 16 opens the arcing contacts 3 and 4. Uponthe separation of arcing contacts 3 and 4 a blast is provided whichsweeps the arcing contacts 3 and i and their engaging surfaces. Whilethe lines of flow of the air blast follow a complicated pattern'whichvaries during the interrupting process, in effect the blast is directedin substantially a single direction transverse to the movement of themovable arcing contact 4 and extinguishes the arc occurring uponseparation of arcing contacts 3 and 4. The transverse air blast may beperpendicular with respect to the direction of movement of contact 4 ormay be oblique withv respect thereto.

The path of the current flowing through arcing contacts 3 and 4 bendssharply near the contact engaging surfaces thereof, thus, forming aloopshaped current path which produces a magnetic means for aiding inbiasing the are formed upon initial separation of the arcing contactsinto chamber 9 downstream of the orifice formed by the guiding means 43of nozzle 82.

Upon a predetermined travel of rod 23 which is actuated by piston IS, aportion thereof abuts against lever 31. The movement of lever 3'! movesone arm thereof out of the path of movement of the movable disconnectcontact 3.

Upon the flow of the air blast through conduit 4|, air under pressuretherefrom is transmitted through a conduit 10 connected thereto and tothe left hand side of motor 33. This pressure impulse moves the pistonof motor 33 from left to right, thus resulting in the separation of thedisconnect contacts 5 and 6. If thedesired predetermined sequence of theactuating means for operation of the arcing contacts 3 and 4 and thedisconnect contacts 5 and 6 does not occur, the lever 37 will preventdisconnect contacts 5 and 6 from separating. However, upon the propersequence of operation lever 3! will be moved out of the path of movementof disconnect contacts Sand 6 without physical contact therewith beforefluid motor 33 actuates disconnect contacts 5 andB.

Upon the flow of an air blast through conduit 4|, air under pressuretherefrom is transmitted through a conduit H to valve 58. This pressureimpulse closes valve 58 and precludes the possibility of air underpressure being supplied to motor 33 through conduit 59, which mightresult in improper closing of the disconnect contacts 5 and 6.

Although but one embodiment of the present invention has beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the inventionor from the scope of theappended claims. F

It is claimed and desired to secure by Letters Patent:

1. In an electric switching device the combination of an arcing chamberhaving an orifice, a discharge passage for said chamber, a source offluid under pressure connected to said chamber to: cause a blast offluid to pass through said orifice and said passage, a pair ofcooperating arcing contacts arranged within said chamber to initiate anarc and comprising a fixed contact and a movable contact having mutuallyengageable surfaces, said movable contact arranged when in the closedposition thereof to completely obstruct said orifice and in the openposition thereof to direct substantially all of said fluid passingthrough said orifice over the said engageable surfaces of said contactsin substantially a single direction transverse to the direction ofmovement of said movable contact, said fixed contact forming an arcrunner for directing the arc downstream from said orifice, an auxiliarycontact arranged within said passage, and a resistor arranged outside ofsaid chamber and connecting said auxiliary contact with one of saidarcing contacts.

2. In an electric switching device the combination of an arcing chamberhaving an orifice, a

discharge passage for said chamber, a source of fluid under pressureconnected to said chamber to cause a blast of fluid to pass through saidorifice and said passage, a pair of abutting arcing contacts arrangedwithin said chamber for initiating an arc and comprising a fixedcontact, the contact engageable surface of which forms a part of thesurface surrounding said orifice, an arc runner forming a part of saidfixed contact for directing one terminal of the arc from said chamber tosaid passage, and a movable contact arranged when in the closed positionthereof to completely obstruct said orifice and in the open positionthereof to direct substantially all of said fluid passing through saidorifice over the engageable surfaces of said contacts in a singledirection transverse to the direction of movement of said movablecontact, an auxiliary contact arranged Within said passage, and aresistor arranged outside of said chamber and connecting said auxiliarycontact with one of said arcing contacts.

3. In an electric switching device the combination of an arcing chamber,a pair of separable abutting arcing contacts arranged within saidchamber for initiating an arc, means for separating said arcing contactsto provide a gap therebetween, means connected to said chamber forproducing an arc extinguishing blast of fluid under pressure across saidgap, guiding means within said chamber and surrounding said contacts andsaid gap for defining a nozzle to direct substantially all said fluidpassing through said gap over the engageable surfaces of said contactsin a single direction substantially perpendicular to the direction ofmovement of one of said contacts, said contacts when in the closedposition thereof completely obstructing said nozzle, said nozzlecomprising a first portion extending from the upstream end of saidguiding means to said gap, a second portion extending through said gapsubstantially perpendicularly to the longi tudinal axis of said gap, anda third portion extending from said gap to the downstream end of saidguiding means, said first portion defining a concave surface and saidthird portion defining a concave surface, an arc runner forming a partof one of said arcing contacts for providing a path for movement of oneterminal of said are downstream of said nozzle, and means for providinga loop shaped path for the arc current including the said engageablesurfaces of said contacts for magnetically biasing the are formed uponinitial separation of said contacts from the gap formed between saidcontacts into said nozzle.

4. In an electric switching device the combination comprising a cylinderforming an arcing chamber, a pair of cooperating arcing contactsarranged within one end of said cylinder along the longitudinal axisthereof to initiate an arc and guishing blast of fluid to flow insubstantially the opposite directions adjacent the arc, guiding meanswithin said chamber and surrounding said contacts to directsubstantially all of said arc extinguishing blast of fluid over theengageable surfaces of said contacts in a single direction substantiallyperpendicular to the direction of movement of said movable contact, saidfixed contact providing an arc runner for directing one terminal of saidare downstream of said guiding means, an auxiliary contact arrangedwithin said chamber substantially along the longitudinal axis thereofdownstream of said arcing contacts, and a resistor arranged outside ofsaid chamber and connecting said auxiliary contact with one of saidarcing contacts.

5. In an electric switching device the combination comprising an arcingchamber having an oriflce, a pair of cooperating arcing contactsarranged within one end of said chamber to initiate an arc andcomprising a fixed contact and a movable contact having mutuallyengageable surfaces, said contacts when in the closed position thereofsubstantially completely obstructing said orifice, a fluid motor of thereciprocatory type arranged within another end of said chamber foractuating said movable contact, means comprising a single source offluid under pressure connected to said chamber between said ends thereoffor causing a first blast of fluid to flow in one direction foractuating said motor and for causing a second arc extinguishing blast offluid to flow in an opposite direction adjacent said arc, said contactarrangement delaying said second blast until said contacts are opened bysaid motor in response to said first blast whereby the fluid suppliedfrom said source to said chamber is initially trapped in said chamber tocause said motor to rapidly open said contacts, and guiding means withinsaid chamber and surrounding said contacts and said orifice to directsubstantially all of said arc extinguishing blast of fluid passingthrough said orifice over the engageable surfaces of said contacts in asingle direction substantially perpendicular to the direction ofmovement of said movable contacts.

CHESTER D. AINSWORTH.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,049,328 Skeats July 28, 1936 2,049,996 Clerc Aug. 4, 1936'2,392,647 Cox Jan. 8, 1946 2,451,669 Eichenberger Oct. 19, 1948 FOREIGNPATENTS Number Country Date 85,565 Sweden Feb. 18, 1936

